This application claims priority under 35 U.S.C. Section 119 from Japanese Patent Application No. 2000-215083, No. 2000-215084, and No. 2000-215085 filed on Jul. 14, 2000 and a Japanese Patent Application No. 2000-385930 filed on Dec. 19, 2000, which is incorporated herein for all purpose.
The present invention relates to a bumper for an automobile, and more particularly to a bumper core that is excellent in impact absorption and integrally disposed in the bumper.
Automobile bumpers ideally provide protection in the event of serious collisions. It is also desired that the bumper have energy absorbing properties to lessen the severity of the accident.
Bumpers should have the ability to deform during smaller accidents and to return to the original shape without incurring expensive repairs. In addition to these concerns, there are also automotive requirements that ensure the bumpers can withstand certain safety requirements.
While most vehicles have both front and rear bumpers, the automobile industry recognizes that the requirements differ between the front and rear bumpers. Front bumpers are usually configured to have greater rigidity in order to accommodate a more severe crash. Rear bumpers generally are made to absorb less severe crashes and to return to the original shape in minor collisions.
The more common bumper has an outer shell and a rigid bumper beam. The bumper beam is a longitudinal reinforcing member, generally tubular, that is affixed to the car body. This metal reinforcing member provides the structural strength in the event of a collision. These are well known in the art and provide satisfactory protection for severe crashes. In minor collisions these bumpers tend to be easily dented and damaged. Thus, repair costs are higher on these vehicles, which affects insurance characteristics, such as the one disclosed in Japanese Patent Application Laid-open No. 3-125649.
Also in the prior art is the use of foam cores that are used primarily in rear bumpers, but also in some front bumpers depending upon the type of vehicle and the cost. It is well known in the industry that to enable a more satisfactory bumper design, it is necessary to combine an outer skin or fascia, some compressible impact absorbing member and a rigid longitudinal member. The foam cores provide some protection in minor crashes by returning the bumper to the original shape. The prior art describes automobile bumpers with an impact absorbing member and front and rear tubular beam reinforcing members disposed inside of a bumper fascia.
In the automobile bumper disclosed in JP-A No. 3-125649, the impact absorbing member and beam reinforcing member are both arranged inside the bumper fascia. However, since the spacing between the bumper fascia and the car body is narrow, it is hard to obtain a sufficient thickness of the impact absorbing member and beam reinforcing member combined in the longitudinal direction for absorbing impact from the outside. This is particularly evident in the rear bumper having a thin and curved shape. These prior art bumper foam members also are expensive to manufacture and integrate into the bumper assemblies. Thus, the prior art foam core is expensive to integrate into a bumper and also has poor impact absorbing properties.
Thus, the prior art design provides insufficient impact absorbing properties and the bumper is likely to suffer denting and damage from even low level impacts. What is needed is a bumper core that is cost-effective to manufacture and install within the bumpers. This bumper core should be designed to withstand significant impact forces and still return to the original shape of the bumper. Such a bumper should increase safety margins as well as lower insurance costs for minor collisions.
The present invention has been achieved in view of the above-described problems of conventional technologies.
Accordingly, the invention provides for an automobile bumper, comprising a bumper fascia having at least one impact absorbing bumper core attached to an inner surface thereof, the bumper core comprising a hollow body defined by a surface wall attached to the bumper fascia, a rear wall opposed thereto, and a pair of opposed side walls, wherein at least one rib extends within the body from the surface wall to the rear wall. The bumper core is disposed between the inside of the bumper fascia and the car body in a hollow double wall structure in order to provide a bumper which has excellent impact absorption from the outside and is also superb in safety. This bumper provides impact absorbing qualities even in a structure with a thin bumper core in the longitudinal direction between the inside of the bumper fascia and car body, such as the rear bumper.
The automobile bumper cores may be interposed between the bumper fascia and the car body at the inside right and left positions as separate units. The bumper cores are formed in a hollow double wall structure by blow molding of thermoplastic resin as a molded body having a hollow part and having sidewalls upright in the longitudinal direction of the bumper fascia. These units are produced as separate units for the right and left sides of the bumper and easily installed by adhesive or other means known in the art.
The automobile bumper cores of the present invention are preferably composed of thermoplastic resin, and even more preferable if having a modulus of flexural elasticity is 10000 kg/cm2 to 40000 kg/cm2, and the overall mean wall thickness is 0.5 mm to 4.0 mm, and the product of modulus of flexural elasticity and mean wall thickness is 1000 kg/cm to 10000 kg/cm.
The present invention provides an impact absorbing automobile bumper core, comprising a surface wall and an opposing rear wall, and with a pair of opposing sidewalls. The bumper core has one or more ribs and a plurality of hollow portions between said surface wall and said rear wall, and wherein said surface wall attaches to an inner surface of a bumper fascia and said rear wall is attached to an automobile.
The automobile bumper has one or more bumper cores formed in a structure having a buffer section composed of a rib for linking between the surface wall corresponding to the inside of the bumper fascia and the rear wall corresponding to the car body.
The impact absorbing automobile bumper core may comprise a surface wall and an opposing rear wall, and a pair of opposing sidewalls. The bumper core has one or more ribs and a plurality of hollow portions between the surface wall and said rear wall, and wherein the surface wall attaches to an inner surface of a bumper fascia. The bumper fascia can attach directly to the car body or connect to a longitudinal structure that is attached on some automobiles.
The bumper fascia may be attached in a longitudinal manner to an automobile in a longitudinal manner having a driver side section,and a passenger side section, wherein said bumper core sections are affixed to said inner surface of the bumper fascia at a driver side and a passenger side.
The rib for linking between the surface wall corresponding to the inside of the bumper fascia and the rear wall corresponding to the car body may be composed of plural concave ribs. The concave ribs are preferably formed in a circular or elliptical sectional shape.
The bumper core are preferably characterized by an integral structure in which the concave ribs composing the buffer section are formed from the surface wall and rear wall, and abutting and fusing in the hollow space.
The circular concave ribs preferably contract in diameter in the hollow space direction from the opening end of the surface wall or rear wall, the diameter of the contracting angle xcex1 being 5 to 30 degrees, and the diameter xcex2 of the opening end being 10 to 40 mm.
In one embodiment, part of the sidewall of the bumper core is indented to the hollow space side to form ribs of the molded body. The rib portion may be formed by indenting part of the sidewall of the bumper core to the hollow space side is semicircular, the rib portion being contracted in diameter in the hollow space direction from the opening end of the surface wall or rear wall of the impact absorbing member, the diameter contracting angle xcex1 is suitably 5 to 30 degrees, and the radius xcex2 of the opening end is suitably 5 to 20 mm.
The bumper cores may have a plurality of coupling ribs for integrally linking the plurality of concave ribs. Each coupling rib of the bumper cores is preferably a longitudinal rib extending from the surface wall in the rear wall direction, or from the rear wall in the surface wall direction.
The bumper of the invention provides impact absorbing qualities even in a structure with a thin bumper core in the longitudinal direction between the inside of the bumper fascia and car body, such as the rear bumper.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention.